House-broken animals, such as cats, are trained into the habit of urinating and defecating in a specially provided litter box. Similarly, untrained and caged animals, such as guinea pigs, urinate and defecate on the floor of their cage, often in approximately the same floor area of the cage. Consequently, pet owners, homeowners, veterinarians and laboratory personnel have added absorbent materials to the litter box or cage to collect the urine and faces. After a relatively short period of time, the dross soiled absorbent emits objectionable odors because of the presence of the urine and fecal matter.
In order to reduce or eliminate these objectionable odors, homeowners periodically remove the fecal matter from the litter absorbent physically. However, physical removal of the feces does not reduce or eliminate odors caused by the urine absorbed into the absorbent. Therefore, when the odors caused by the absorbed urine become intolerable, the homeowner discards the litter box absorbent material entirely. The homeowner then washes the litter box and refills the litter box with fresh litter box absorbent material. These activities are unpleasant, time-consuming and expensive. Consequently, the litter box absorbent material usually is a relatively inexpensive solid absorbent material, such that an individual cleaning of the litter box is not particularly economically burdensome. However, repeated litter box cleanings over a period of time accounts for relatively large expenditures.
The most commonly used litter box absorbent materials are inexpensive clays, such as calcined clays, that are safe and non-irritating to the animals, and that absorb relatively substantial amounts of liquids. Other porous, solid litter box absorbent materials, that are used alone or in combination, include straw, sawdust, wood chips, wood shavings, porous polymeric beads, shredded paper, sand, bark, cloth, ground corn husks, cellulose, and water-insoluble inorganic salts, such as calcium sulfate. Each of these absorbent materials has the advantage of low cost, but each suffers from the disadvantage of merely absorbing a liquid waste product and holding the product within its porous matrices, or, in the case of sand, absorbing the liquid dross on its surface. For each absorbent material, offensive odors are eventually caused by the absorbed urine, and the entire contents of the litter box, including soiled absorbent material and unsoiled absorbent material, has to be discarded.
One such litter box absorbent material is described in Lohman U.S. Pat. No. 4,570,573. The Lohman patent is directed to an animal litter composition comprising about 60-94% by weight paper, about 1-35% calcium sulfate and about 3-12% water. Such an absorbent is effective in collecting animal dross, but it does not reduce or eliminate the generation of objectionable odors and does not eliminate the disadvantage of periodically replacing the entire contents of the litter box. Larson et al in U.S. Pat. No. 4,315,761 describes the use of aerated or foaming concrete, of relatively large size, for example, up to 10 mm (millimeters), to absorb animal dross and facilitate removal of the excrement from a litter box. The aerated concrete merely absorbs the animal dross, and therefore suffers from the identical drawback of present day animal litter box compounds, i.e., an inability to easily separate the soiled absorbent particles from the unsoiled absorbent particles without having to clear and clean the entire litter box.
Stuart, in U.S. Pat. No. 4,685,420, discloses an improved litter box absorbent composition comprising from 0.01% to 5.0% by weight of a water-absorbing polyacrylate in combination with a common litter box absorbent material. According to the method and composition of Stuart, the polyacrylate and absorbent material absorb the urine or similar waste material, and the polyacrylates act to gel the soiled litter box absorbent material into a gelled product. Stuart teaches that the gelled absorbent material then can be physically removed from the litter box to reduce the generation of offensive odors, and to avoid discarding the unsoiled portion of the absorbent material. However, the method and composition of Stuart suffers from the disadvantage of relative cost ineffectiveness. The commonly used litter box absorbent materials are very inexpensive materials, whereas the water-absorbent polymers of Stuart are relatively expensive products that can raise the initial cost of the litter box absorbent material to an unacceptable level in a very cost competitive market.
Other litter box absorbent materials are disclosed by Fisher in U.S. Pat. No. 3,765,371 describing a foamed plastic for absorbing and/or absorbing animal dross; by Kramer et al in U.S. Pat. Nos. 4,275,684 and 4,395,357 describing calcium silicate as an animal litter box absorbent material and specifically teaching against the use of mineral products, such as clay-type minerals, because of the mineral product's tendency to swell upon liquid absorption; by Rodriguez et al in U.S. Pat. No. 4,494,481 describing the addition of a transmission metal of Group Ib or IIb of the periodic table to present-day litter box absorbent materials to prevent the development of urine odors; and by Greenberg in U.S. Pat. No. 4,638,763 describing the addition of sodium sulfate to a litter box absorbent material to facilitate removal of soiled absorbent from the litter box.
Unicharm KK Japanese application J63044-822-A discloses a clay pet litter containing an organic acid and its salt as a deodorant. The clay litter of the present invention is natural clay, as mined and ground, that functions to agglomerate liquid animal dross for effective removal of the used liquid-soaked litter without organic acid or other chemical treatments.
Kenkyu Japanese application J6 1119-127-A discloses spraying a cyanoacrylic acid alkyl ester film on the surface of pet feces for removal of the feces separately from the litter.
Crampton et al U.S. Pat. No. 4,657,881 teaches a pet litter formed from compacted fines of bentonite clay or other clays such that after compaction, the clay particles have a size of 710 microns to 4 millimeters. Such compacted clays have been found to be very adherent to an animal's paws and fur after wetting.
In accordance with the present invention, it has been found that the compaction of fine particles into larger particles within applicant's preferred particle size range of about 600 microns to about 3350 microns produces a pet litter that is muddy when wetted, apparently due to particle size breakdown upon wetting, and incapable of quick absorption of liquid to form cohesive, non-sticky masses even after partial drying, e.g. 12-24 hours at room temperature, so that the wetted animal dross-soaked litter when compacted, is often removed from the litter box by the animal's paws and fur necessitating frequent and irritating household cleaning. To achieve the full advantage of the present invention, the water-swellable clay used as a pet litter material in accordance with the present invention should have a particle size within the range of about 50 microns to about 3350 microns, and preferably 600 microns to about 3350 and should not be compacted from finer particles.
Therefore, a need exists for a litter box absorbent material that effectively collects the urine or other dross material of house-broken pets and caged animals; that agglomerates when wetted to allow physical removal of the wetted litter box absorbent material from unwetted litter box absorbent material in order to reduce or eliminate dross-based odors and to reduce costs associated with animal litter box absorbent materials; that will be relatively non sticky when wetted by animal dross to form a cohesive mass that will not stick substantially to the animal so that it can be retained within the litter box as a cohesive non-muddy mass until removed by the animal's caretaker; that will be relatively non sticky when wetted by animal dross to form a cohesive mass that will not stick substantially to the animal so that it can be retained within the litter box as a cohesive non-muddy mass until removed by the animal's caretaker; that is capable of spontaneous dispersion in water after agglomeration so that the material can be discarded to a household waste or storm sewer line, for example, by flushing the dross-soaked, dispersed agglomerates down a household toilet, without clogging plumbing lines; and that is sufficiently economical for practical use in a highly competitive and cost conscious market. Surprisingly and unexpectedly, it has been found that non-compacted water-swellable bentonite clays having a particle size in the range of about 50 microns to about 3350 microns, and preferably about 600 microns to about 3350 microns effectively absorb animal dross, and during absorption of the animal dross, agglomerate into a sufficiently large, stable and non-sticky mass for physical separation of the liquid dross-soiled portion of the litter box absorbent material from the unused portion of the litter box absorbent material even after partial drying e.g. 1 to 24 hours at room temperature, and remains cohesive and non-adherent to the animal even after a 24 hour drying period at room temperature. The water-swellable bentonite clays, and their absorbent and agglomerating properties, effectively reduce or eliminate odors associated with animal dross; reduce costs associated with litter box absorbent material replacement; and are sufficiently economical to compete effectively in a highly competitive and cost conscious industry.
In another embodiment, it has been found that a combination of non-compacted sodium bentonite, in an amount of about 1% to about 50% by weight, and calcium bentonite, either compacted or non-compacted, in an amount of about 50% to about 99%, by weight, based on the total weight of clay in the composition, effectively absorbs animal dross, and during absorption of the animal dross, agglomerates into a sufficiently large and stable mass for physical separation of the soiled portion of the litter box absorbent material from the unused portion of the litter box absorbent material, such that the agglomerates readily and spontaneously disperse in water for disposal through a household sewer conduit. To achieve the full advantage of this clay mixture embodiment of the present invention, the combination of sodium bentonite and calcium bentonite clays should have a particle size in the range of about 50 microns to about 3350 microns, and preferably about 600 microns to about 3350 microns.